Occasionally, there will be a few cases where a random encounter table includes two monster factions fighting each other.

Otherwise, its mostly there to allow player characters who can speak Goblin to get various missions from the goblins in exchange for things like info or admittance through a highly patrolled area of the dungeon, etc. The players can also play the monster factions against one another. The ripple effects of this are open to interpretation, but probably include the monsters slowly becoming more and more united and escalated against the ever-increasing challenge rating of these douchehole surface dwellers who keep making a mess of things.

The monsters probably deserve it, but the escalation will kill you. The PARTY might even be responsible for creating the campaign's "dark lord" character who unites the monsters to spell doom for the forces of good and law.

Would air also be a resource? Perhaps air-purifying mushrooms ... another simple resource is also probably fuel: those kobolds follow monsters around to harvest their dung, so they can cook their rats ...

Pool of animating water seems like a great monster generating excuse. Every day roll to see what new thing it has spawned:1) The fountain statue/golem2) Water elemental/weird3) Mud men4) Zombies (of creatures who drown there overnight)5) Clear oozes or jellies6) Air elemental (if it was windy overnight)